ABSTRACT The main objective of this grant is to determine the mechanisms by which chymotrypsin C (CTRC) mutations act as risk factors for chronic pancreatitis in humans. The project forms a part of our broad, long-term research program to understand the molecular mechanisms of genetic risk factors associated with human pancreatitis. These studies so far combined biochemical and cell biological approaches with data obtained from human genetic association studies to formulate a molecular disease model for recurrent acute and chronic pancreatitis. Our current working hypothesis is that genetic risk in pancreatitis is mediated via two independent pathological pathways, which can result in acinar cell damage. In the trypsin-dependent pathological pathway intra-pancreatic autoactivation of trypsinogen to active trypsin is responsible for cell injury; whereas in the misfolding-dependent pathological pathway retention of misfolded mutant proteins can damage acinar cells through induction of endoplasmic reticulum stress. In the previous funding period we established that CTRC mutations are highly significant risk factors for chronic pancreatitis and these mutations exert their effect primarily through the trypsin-dependent pathway, while a subset of CTRC mutants also engages the misfolding-dependent pathway. In the next funding period our aim is to validate our conclusions in vivo and create and characterize mouse models that will test whether genetic deletion of mouse Ctrc increases intra-pancreatic trypsinogen activation and pancreatitis responses; and whether transgenic expression of a misfolding human CTRC mutant in the mouse pancreas causes endoplasmic reticulum stress, acinar cell damage and increased susceptibility to pancreatitis.